Soprafino. Because it's such a classic and everything a tarot deck should be.
The others are nice but there is something so timeless and universal about the Soprafino.
Sorry but the Ancient Italian is nothing like the Soprafino really. It has rougher lines. The Soprafino is so much more delicate. I got a second copy and, heathen that I am, rounded the corners. It's the one I use the most.
It's the most desirable of all Menneghello decks and when it's gone, it's desirability will multiply in a way the others won't (OK, that's just my personal opinion).
The Vacchetta is my least favourite. the Neoclassical, lovely but somehow lacking in details for meaty readings. The Soprafino is adored across the board, regardless of taste. Wherever you're coming from, whatever your tastes, ´tis heavenly.